1. Field of the Invention
The present invention relates to a printer.
2. Description of the Related Art
Various types of thermal printers that perform printing by pressing a thermal head against a thermal recording sheet and emit color by heating are currently provided. In particular, the thermal printers are suitably used for printing various types of labels, receipts, tickets, and the like because printing of smooth characters and colorful graphic printing can be realized without using toner, ink, and the like.
As represented by a thermal printer, various printers with a cutter for cutting the printed recording sheet, are known. The cutter (auto cutter) including a drive source is normally set to automatically cut the recording sheet when the printing is completed, and hence the cut recording sheet can be rapidly used as receipt, ticket, and the like.
The thermal printer is used while being incorporated in a cash register, portable terminal device, and the like.
The thermal printer includes a casing provided with a housing unit for a roll-type recording sheet (roll sheet), and an open/close door of the roll sheet housing unit. A casing is mounted with a main body unit, and the open/close door is mounted with a cover unit. The main body unit supports a thermal head and the cover unit supports a platen roller for feeding the roll sheet. The thermal printer also includes a platen drive system for rotatably driving the platen roller.
The cutter includes a fixed blade, and a movable blade that linearly moves so as to approach to or separate from the fixed blade. For instance, the fixed blade is supported by the main body unit, and the movable blade is supported by the cover unit. When cutting the recording sheet, the recording sheet is sandwiched and cut with both blades like with scissors by moving the movable blade toward the fixed blade.
The thermal printer also includes a movable blade drive system for moving the movable blade. The movable blade drive systems adopting a rack-pinion type, a cam type, or the like are known. The movable blade drive system adopting the rack-pinion type includes a rack constructed integrally with the movable blade, a pinion gear that meshes with the rack, and a pinion drive system for driving the pinion gear.
Patent Document JP 2001-121764 A describes a printer in which the movable blade drive system is mounted on the cover unit. In the invention of Patent Document JP 2001-121764 A, the weight load applies on the hinge portion of the open/close door because the cover unit becomes heavy, and may be detrimental to the opening/closing operation of the open/close door due to change over time. Further, the electrical wiring of the movable blade drive system is formed on the main body side, and hence the wiring may break in accordance with the opening/closing of the cover. The drive system may break down due to vibration and impact in opening and closing.
Patent Document 2 describes a printer in which part of the movable blade drive system is mounted on the cover unit. FIG. 8B is a schematic configuration diagram of the printer described in Patent Document JP 2004-237555 A. In this printer, at least a rack 44 and a pinion gear 42 of the movable blade drive system are mounted to a cover unit 3. This printer has a driving wheel train mechanism mounted to the cover unit that is subjected to vibration and impact in opening and closing, and thus may break down.
In both inventions of Patent Documents 1 and 2, an acting point for moving the movable blade is at a backward position of the movable blade (movable blade push-out method). In this case, a large rotational moment acts on the cover unit due to a sheet cutting reaction force that acts from the fixed blade to the movable blade and a frictional force between the fixed blade and the movable blade. Due to such rotational moment, bite occurs in a direction the fixed blade and the movable blade open, the pressure between the fixed blade and the movable blade lowers, and the cutting operation becomes unstable. As a result, the cutting performance lowers.